The prior art, U.S. Pat. No. 3,290,037, provides for an oleo-pneumatic shock absorber for separate programming at landing impact and during subsequent roll-out wherein it is necessary to orient the absorber in or near the vertical position. In the more complex undercarriages employed on some aircraft comprising, for example, multiple wheel units or bogies vertical or near vertical orientation of the absorber may not be desirable nor even possible.